1. Field of the Invention
The present invention relates to an ink-jet recording apparatus comprising a carriage which performs reciprocating motion in the widthwise direction of a recording medium; an ink-jet recording head mounted on a carriage; and an ink supply system which is mounted on the carriage and supplies ink to the recording head.
2. Background Art
An ink-jet recording apparatus to be used for producing a large volume of printed matter is disclosed, for instance, in Japanese Patent Kokoku Publication No. Hei. 4-43785 and Japanese Patent Kokai Publication No. Hei. Hei. 10-44685. The apparatus disclosed in the former publication is constructed such that ink to be consumed in a printing operation is supplied to a recording head through a sub-tank, which is disposed on a carriage and connected through an ink supply tube to an ink container, such as a cassette, on a housing of the apparatus. The apparatus disclosed in the latter publication includes a sub-tank which is disposed on a carriage and supplies ink to an ink-jet recording head; an ink cartridge installed on a housing of the apparatus; and an ink replenishing unit which is connected through a conduit to the ink cartridge and removably connected to the sub-tank so that the sub-tank is intermittently replenished with a desired amount of ink.
Precise flow control is required to supply ink from the ink replenish unit to the sub-tank of a relatively small capacity without causing ink leakage, and thus a complicated valve mechanism is required.
For this reason, as disclosed in Japanese Utility Model Kokai Publication No. Hei. 3-77641 and Japanese Patent Kokai Publication No. Sho. 62-263059, it is conceivable to monitor liquid level of ink, i.e. an ink amount, in the tank with such an arrangement that a float member incorporating magnetic material is provided in an ink tank so as to be vertically movable along a guide, and a magnetic detection system is disposed outside the ink tank. This arrangement, however, suffers from problems in that the range where ink level can be detected is narrow, and idle time required for ink replenishment is long, resulting in lower throughput.
The present invention is preferably applicable to an ink-jet recording apparatus which has a recording head mounted on a reciprocating carriage, which receives supply of ink from an outside, and which, in turn, supplies ink to the recording head.
In a preferred embodiment, an ink storage chamber receives supply of ink from an outside, a float member is movable to follow liquid level of the ink stored in the ink storage chamber, an indicator is provided to the float member, and a plurality of detection systems provided opposite the indicator and arranged vertically. The detection systems cooperatively detect the indicator when the ink stored in the ink storage chamber is maintained within an appropriate range of volume. At least three statuses of ink level can be detected using signals from the detection systems, on the basis of which replenishment of ink is controlled.
Accordingly, the present invention is aimed at providing an ink-jet recording apparatus having a sub-tank, which detects variations in ink level over a wide range using a plurality of sensors, thereby maintaining ink at an appropriate level.
The present disclosure relates to the subject matter contained in Japanese patent application Nos.:
Hei. 11-315071 (filed on Nov. 5, 1999);
2000-012461 (filed on Jan. 21, 2000);
2000-024422 (filed on Feb. 1, 2000);
2000-235404 (filed on Aug. 3, 2000);
2000-299698 (filed on Sep. 29, 2000);
2000-323963 (filed on Oct. 24, 2000); and
2000-331252 (filed on Oct. 30, 2000),
which are expressly incorporated herein by reference in their entireties.